NetworkServerUDP: introduce _uniqueID, simplify logging, deserialize using packet...

NetworkServerUDP: introduce _uniqueID, simplify logging, deserialize using packet length

 * Introduce _uniqueID
 * Simplify logging
 * Use packet length when deserializing
 * No longer update ServiceAddressMap

Introduce _uniqueID. Tag each outgoing NetworkMessage with this
service's unique ID to provide accurate loopback detection in receiver.

Use the super class simplified logging.

Pass the received DatagramPacket length when deserializing
NetworkMessage.

Do not try to update ServiceAddressMap. Leave to the NetworkMessageEventListener
which can access the messages contained within the NetworkMessage wrapper.